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This article deals with the influence of shear stress on endothelial NO synthesis, and the role of caveolae in shear stress-induced eNOS activation. Human umbilical vascular endothelial cells (HUVEC) were cultured and exposed to different levels of laminal shear stress and Filipin, the perfused cultures were collected, and NO(2-)/NO(3-) was detected using nitrate reduction method. The structure of caveolae was observed through transmission electron microscopy (TEM). The level of NO(2-)-/NO(3-) was found to increase with the elevation of shear stress level (P < 0.01). It was the highest at 1.5 N/m2. After treatment with Filipin, the level of NO produced by HUVEC decreased significantly (P < 0.01), but after recovery and shear without Filipin, the level of NO synthesis bounded back (P < 0.01). It was then concluded that shear stress can induce endothelial NO synthesis and caveolae plays a key role in shear stress-induced eNOS activation.
Subject(s)
Humans , Caveolae , Physiology , Cells, Cultured , Endothelium, Vascular , Cell Biology , Filipin , Pharmacology , Nitric Oxide Synthase Type III , Metabolism , Shear Strength , Umbilical Veins , Cell BiologyABSTRACT
Objective:To observe the affection of angiotensin Ⅱ antagonists on the cultured subtype 2 receptor of angiotensin II transfected aortic vascular smooth muscle cells of rat.Methods:After transfected the plasmid that contained the cDNA of subtype 2 receptor of angiotensin II into cultured rat vascular smooth muscle cells, the cells were divided into three groups：cells of group 1 were treated with angiotensinⅡ,cells of group 2 were treated with angiotensinⅡand losartan,cells of group 3 were treated with angiotensinⅡ and PD123319 .After experiments，the expression of PCNA, NOS and the cell number was tested, respectively.Results：After treated with Losartan，the cell number of group 2 was(4.17±0.15)×105，the OD value of PCNA was 0.202 6±0.007 6，both of which were less than that of cells of group 3；the OD value of NOS of cells was more in group 2(0.027 5±0.002 1 ) than that in group 3 (0.016 9±0.002 0) (P＜0.01).Conclusions:It suggests that when being activated,subtype 2 receptor of angiotensin Ⅱ could inhibit the proliferation of vascular smooth muscle cells and antagonist the effect of subtype 1 receptor of angiotensin Ⅱ,such an effect may be related to the activation of NOS.
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AIM：To analyse sequences of p62dok amino acid and cDNA and to investigate p62dok tyrosine phosphorylation and its relation with p21ras GAP. METHODS：The purified p62dok was extracted from CHO/IR cells. The peptide sequence of p62dok was carried out on a high performance analyzer. PCR was performed with the primers designed from the sequence of p62dok amino acid. Western blot and immunoprecipitation were used to identify tyrosine phosphorylation of p62dok and the binding of p62dok with p21ras GAP. RESULTS：The p62dok cDNA is a 1863 bp sequence and code 481 amino acid with 15 tyrosine residues and a putative pleckstrin homology domain. The p62dok protein is rich in PxxP motif. The tyrosine-phosphorylated p62dok can bind p21ras GAP. CONCLUSION：Perhaps p62dok is a new signaling molecule and play an important role in insulin signaling networks through RAS/MAPK pathway.
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AIM and METHODS: The protective effects of multi-enzyme Ⅱ was studied on cultured endothelial cells which was injuried by hyperlipidemia serum. RESULTS: Hyperlipidemia serum increased ICAM-1 expression on the surface of endothelial cells, and decreased NO- 2 release significantly (P
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AIM: To study the effect of thyroid hormone on the expressional change of myosin heavy chain(MHC) gene in cardiomyocyte induced by angiotensinⅡ(AngⅡ) and its potential mechanism. METHODS: Cardiac myocyte was cultured according to the method of Simpson. 10 -8 mol/L T_3 and 10 -7 mol/L AngⅡ were added to the culture medium,respectively or synchronously. After 48 h,the expression of ? and ?-MHC mRNA in myocytes were detected by RT-PCR. The protein kinase C activation were detected by PepTag non-radioactive PKC assay. The incorporation of -Leucine and -thymine to test the protein and DNA synthesis in myocytes were also performed. RESULTS: AngⅡalone increased the incorporation of -Leucine of myocytes while it had no effect on the incorporation of -thy mine. The expression of ?-MHC mRNA was increased and the expression of ?-MHC mRNA was decreased significantly at the condition of AngⅡ. The enhanced PKC activation was induced by AngⅡalso. When AngⅡand T_3 were added to the culture medium synchronously,though the incorporation of -leucine and -thymine were not changed compared with AngⅡ treated alone. The ?-MHC mRNA expression was increased and the ?-MHC mRNA expression was decreased significantly. The PKC activation of the myocytes also was decreased. CONCLUSIONS: T_3 inhibited the expressional change of myosin heavy chain gene in cardiac myocytes induced by AngⅡ. The effect of T_3 on the change of PKC activation in cardiac myocytes may be one of its mechanisms.
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AIM:To analyse sequences of p62 dok amino acid and cDNA and to investigate p62 dok tyrosine phosphorylation and its relation with p21 ras GAP. METHODS:The purified p62 dok was extracted from CHO/IR cells. The peptide sequence of p62 dok was carried out on a high performance analyzer. PCR was performed with the primers designed from the sequence of p62 dok amino acid. Western blot and immunoprecipitation were used to identify tyrosine phosphorylation of p62 dok and the binding of p62 dok with p21 ras GAP. RESULTS:The p62 dok cDNA is a 1863 bp sequence and code 481 amino acid with 15 tyrosine residues and a putative pleckstrin homology domain. The p62 dok protein is rich in PxxP motif. The tyrosine-phosphorylated p62 dok can bind p21 ras GAP. CONCLUSION:Perhaps p62 dok is a new signaling molecule and play an important role in insulin signaling networks through RAS/MAPK pathway.
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AIM To compare the protective effects of norepinephrine preconditioning(NEPC)and ischemic preconditioning(IPC)on myocardial ischemic/reperfused injury in rats in vivo . METHODS Rats were divided into control, ischemia/ reperfusion, classic IPC and NEPC groups. After 20 min reperfusion, several indexes including cardiac function indexes, MDA were tested, the myocardial ultrastr ucture and the injury reaction of catalase observed. RESULTS Both IPC and NEPC could protect myocardial ultra structure, ameliorate left heart function, decrease cardiac MDA content and protect the activity of catalase. CONCLUSION Extra micro norepinephrine preconditioning as a non injury method can mimic the protective effects of classic IPC and shows its clinical values.
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AIM: The effects of BDM on isolated rat heart in cold cardioplegia were studied METHODS: Rat heart were subjected to cold cardioplegia at 4℃ for 8, 18 and 24 h Then each heart was perfused (90 cm H 2O) in Langendorff model at 37℃ for 40 min In the high K + group( n =24) the hearts were preserved in St Thomas cardioplegic solution, in BDM group( n =24) hearts were preserved in K-H solution with BDM 30 mmoL/L RESULTS: After 18 h, heart rate and the coronary flow in BDM group were significantly higher than in high K + group( P
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AIM: To observe the effect of angiotensinⅡ subtype 2 receptor (AT_2 receptor) on the cultured rat aortic vascular smooth muscle cells. METHODS: The plasmid contained the cDNA of AT_2 receptor was transfected into cultured rat vascular smooth muscle cells. The effects of AngⅡ, Ang Ⅱ+losartan, Ang Ⅱ+PD123319 on the expression of PCNA, the NOS activity and the cell number were observed. RESULTS: The cell number and the expression of PCNA decreased after the cells were treated with losartan. When treated with PD123319, the cell number and the expression of PCNA increased, but the expression of NOS decreased. CONCLUSIONS: These data suggest that when being activated, AT_2 receptor inhibits the proliferation of vascular smooth muscle cells and antagonizes the effect of AT_1 receptor, such an effect may be related to the activation of NOS. [